The Wuhuan 烏桓, also written Wuwan 烏丸, were a people roaming the eastern area of modern Mongolia during the Han period 漢 (206 BCE-220 CE). Ancient Chinese historians called them a tribe of the Eastern Hu 東胡. Their ethnic and linguistic affiliation is unclear. Chinese histories say that after the mighty steppe federation of the Xiongnus 匈奴 had forced the Eastern Hu into submission, some of them migrated to Mt. Wuhuan (in the region of Sira Muren River), whose name they later adopted.

The Wuhuan were a nomadic people living of husbandry, but in some places also from agriculture. They were living in felt yurts, and Wuhuan women embroidered animals skins. The men were famous craftsmen producing weapons and bronze and iron tools. They lived in villages of 20 to 30 families that were guided by heads of tribal groups. Larger groups were also headed by a chieftain. This chieftain had the right to convoke all tribal groups for hunting or military campaigns. The penal law of the Wuhuan was very harsh, but it was possible to buy oneself free by offering cows or sheep. Tribal leaders were elected from among the most successful men.

From the 2nd century CE on the position of chieftain became inheritable. The Chinese were particularly astonished about the lack of filial piety among the Wuhuan towards fathers. It was no crime to kill one's father if necessary, but mothers were protected as holders of the genital line. Men used to shave their foreheads, and from marriage on women braided their hair and wore a kind of cap made of the bark of birchtrees. Wuhuan couples had pre-marital relationship, and the married couple lived for some time in the girl's family. It is said the all decisions in a tribe, except war, were made by women. The dead were buried in coffins and were offered dogs, their private horse as well as precious objects. The Wuhuan people believed in demons and ghosts and brought sacrifices to Heaven and Earth, the stars, and the spirits of mountains and rivers.

The mighty federation of the Xiongnu expected the Wuhuan to offer annual tributes of horses, skins, and girls. In 119 BCE general Huo Qubing 霍去病 destroyed the eastern flank of the Xiongnu federation. The Wuhuan were thereafter forced to settle down more eastwards, into the commanderies Shanggu 上谷, Yuyang 漁陽, Youbeiping 右北平, Liaodong 遼東 and Liaoxi 遼西. In the province of Youzhou 幽州, the post of Commandant protector of the Wuhuan (hu Wuhuan xiaowei 護烏桓校尉) was founded who ensured a better control over the steppe peoples and their relations to the Xiongnu. The usurper Wang Mang 王莽 (r. 8-23 CE) even prohibited the Wuhuan from trading with the Xiongnu, with the result that the Xiongnu robbed cattle and slaves from the Wuhuan. He also ordered the Wuhuan to attack the Xiongnu, threatening them to kill their women and children who were held as hostages. In that situation the Wuhuan decided to become vassals of the Xiongnu again. They began raiding the Chinese border commanderies.

Only in 45 general Ma Yuan 馬援 tried to bring them again into line with the border politics of the Later Han empire 後漢 (25-220 CE). The Wuhuan defeated Ma Yuan and a year later were even able to push the Xiongnu back north. Emperor Guangwu 漢光武帝 (r. 25-57 CE) thereupon bribed Wuhuan chieftains, whereupon some of them submitted to the Han empire and presented tributes of quadrupeds, slaves, and furs. They were rewarded with honorific titles of "general", "king" and "marquis", and they were allowed to settle down with their people in the border commanderies of northern China. The institution of Commandant protector was revived. He resided in Ningcheng 寧城 (modern Xuanhua 宣化, Hebei) and supervised tributes, the exchange of hostages and presents, and the border markets.

With the southward migration of the Wuhuan their former territory was occupied by the Xianbei 鮮卑. Those that had remained in the north became parts of the Xiongnu and Xianbei federations and participated in the regular border raids on Han territory. Those living on Han territory were often dispatched to fight against the raiders. During the second century CE, with the increasing weakness of the Han central government, political structures became more fluid, and Wuhuan participated in all various military campaigns. Wuhuan cavalry was also used by the local Han governments to suppress peasant uprisings.

In 185, for instance, cavalry general Zhang Wen 張溫 commanded 3,000 Wuhuan crack troops to put down a rebellion in the province of Liangzhou 涼州 far in the west, yet their continuous use as "cannon fodder" resulted in the desertion of large groups that returned to their homelands in the northeast. In 187 governor Zhang Ju 張舉 and princely counsellor Zhang Chun 張純 rebelled against the Han dynasty. They engaged Wuhuan troops that looted the region of the modern provinces of Shanxi, Hebei, Henan and even Shandong. Zhang Chun adopted the title of King Anding of Mitian 彌天安定王 and marshal of the Wuhuan armies. He died two years later, and the Wuhuan armies disintegrated.

In 190 the Wuhuan chieftain Tadun 蹋頓, son of Qiuliju 丘力居, united all Wuhuan people in the northwest and founded a Wuhuan empire. Fifteen years later the son of the defeaded warlord Yuan Shao 袁紹, Yuan Shang 袁尚, fled to the Wuhuan empire. The mighty warlord Cao Cao 曹操 therefore undertook a campaigns against the Wuhuan in 207 and defeated them in the battle of Liucheng 柳城. Tadun and his officers were executed by the victor. Cao Cao forcibly resettled the Wuhuan to places more south, held many women and children hostages, and used Wuhuan men for his cavalry. The Wuhuan later merged with the peoples of the inner parts of China, or with the peoples of the Xianbei federation in the north.